In a long term evolution (English: Long Term Evolution, LTE for short) communications system, an uplink resource that is required by user equipment (English: User Equipment, UE for short) to send uplink data needs to be allocated by a base station. The UE can send the uplink data to the base station only after the UE obtains the uplink resource allocated by the base station. When allocating the uplink resource to the UE, the base station needs to consider information such as a data volume of the UE, a distance between the UE and the base station, and a category of the UE. The uplink resource includes uplink sending bandwidth.
After obtaining the uplink resource allocated by the base station, the UE calculates sending power that is required for sending the uplink data. The sending power may be simply represented as a product of power spectral density and uplink sending bandwidth. When the UE is relatively distant from the base station, relatively large power spectral density is required to ensure decoding accuracy. Due to a limitation of a hardware condition of the UE, the UE has upper limit power. When sending power calculated by the UE is greater than the upper limit power of the UE, the UE sends the uplink data by using the upper limit power of the UE. The UE further calculates power headroom (English: Power Headroom, PH for short), where the PH is a difference between the upper limit power of the UE and the calculated sending power, and the UE sends a power headroom report (English: Power Headroom Report, PHR for short) to the base station, so that the base station refers to the PH of the UE when allocating the uplink resource to the UE next time. The PHR includes PH of all activated cells (English: cell) in which the UE is located.
Before the UE sends the PHR to the base station, the base station also needs to allocate the uplink resource to the UE for sending the PHR. However, all the activated cells in which the UE is located may include a first cell and a second cell, and a TTI length of the first cell is at least twice a TTI length of the second cell. In this case, there is no solution about how to send the PHR in the prior art.